On 02/12/2013 08:23 PM, Paolo Bonzini wrote: > Move the creation of the request header and response footer to > __virtblk_add_req. vbr->sg only contains the data scatterlist, > the header/footer are added separately using the new piecewise > API for building virtqueue buffers. > > With this change, virtio-blk (with use_bio) is not relying anymore on > the virtio functions ignoring the end markers in a scatterlist. > The next patch will do the same for the other path. > > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
Reviewed-by: Asias He <as...@redhat.com> > --- > drivers/block/virtio_blk.c | 74 ++++++++++++++++++++++++++----------------- > 1 files changed, 45 insertions(+), 29 deletions(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index fd8a689..4a31fcc 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -62,6 +62,7 @@ struct virtblk_req > struct virtio_blk *vblk; > int flags; > u8 status; > + int nents; > struct scatterlist sg[]; > }; > > @@ -100,24 +101,52 @@ static inline struct virtblk_req > *virtblk_alloc_req(struct virtio_blk *vblk, > return vbr; > } > > -static inline int __virtblk_add_req(struct virtqueue *vq, > - struct virtblk_req *vbr, > - unsigned long out, > - unsigned long in) > +static int __virtblk_add_req(struct virtqueue *vq, > + struct virtblk_req *vbr) > { > - return virtqueue_add_buf(vq, vbr->sg, out, in, vbr, GFP_ATOMIC); > + struct scatterlist sg; > + enum dma_data_direction dir; > + int ret; > + > + unsigned int nents = 2; > + unsigned int nsg = 2; > + > + if (vbr->nents) { > + nsg++; > + nents += vbr->nents; > + } > + > + ret = virtqueue_start_buf(vq, vbr, nents, nsg, GFP_ATOMIC); > + if (ret < 0) > + return ret; > + > + dir = DMA_TO_DEVICE; > + sg_init_one(&sg, &vbr->out_hdr, sizeof(vbr->out_hdr)); > + virtqueue_add_sg(vq, &sg, 1, dir); > + > + if (vbr->nents) { > + if ((vbr->out_hdr.type & VIRTIO_BLK_T_OUT) == 0) > + dir = DMA_FROM_DEVICE; > + > + virtqueue_add_sg(vq, vbr->sg, vbr->nents, dir); > + } > + > + dir = DMA_FROM_DEVICE; > + sg_init_one(&sg, &vbr->status, sizeof(vbr->status)); > + virtqueue_add_sg(vq, &sg, 1, dir); > + > + virtqueue_end_buf(vq); > + return 0; > } > > -static void virtblk_add_req(struct virtblk_req *vbr, > - unsigned int out, unsigned int in) > +static void virtblk_add_req(struct virtblk_req *vbr) > { > struct virtio_blk *vblk = vbr->vblk; > DEFINE_WAIT(wait); > int ret; > > spin_lock_irq(vblk->disk->queue->queue_lock); > - while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr, > - out, in)) < 0)) { > + while (unlikely((ret = __virtblk_add_req(vblk->vq, vbr)) < 0)) { > prepare_to_wait_exclusive(&vblk->queue_wait, &wait, > TASK_UNINTERRUPTIBLE); > > @@ -134,22 +163,18 @@ static void virtblk_add_req(struct virtblk_req *vbr, > > static void virtblk_bio_send_flush(struct virtblk_req *vbr) > { > - unsigned int out = 0, in = 0; > - > vbr->flags |= VBLK_IS_FLUSH; > vbr->out_hdr.type = VIRTIO_BLK_T_FLUSH; > vbr->out_hdr.sector = 0; > vbr->out_hdr.ioprio = 0; > - sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); > - sg_set_buf(&vbr->sg[out + in++], &vbr->status, sizeof(vbr->status)); > + vbr->nents = 0; > > - virtblk_add_req(vbr, out, in); > + virtblk_add_req(vbr); > } > > static void virtblk_bio_send_data(struct virtblk_req *vbr) > { > struct virtio_blk *vblk = vbr->vblk; > - unsigned int num, out = 0, in = 0; > struct bio *bio = vbr->bio; > > vbr->flags &= ~VBLK_IS_FLUSH; > @@ -157,24 +182,15 @@ static void virtblk_bio_send_data(struct virtblk_req > *vbr) > vbr->out_hdr.sector = bio->bi_sector; > vbr->out_hdr.ioprio = bio_prio(bio); > > - sg_set_buf(&vbr->sg[out++], &vbr->out_hdr, sizeof(vbr->out_hdr)); > - > - num = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg + out); > - > - sg_set_buf(&vbr->sg[num + out + in++], &vbr->status, > - sizeof(vbr->status)); > - > - if (num) { > - if (bio->bi_rw & REQ_WRITE) { > + vbr->nents = blk_bio_map_sg(vblk->disk->queue, bio, vbr->sg); > + if (vbr->nents) { > + if (bio->bi_rw & REQ_WRITE) > vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; > - out += num; > - } else { > + else > vbr->out_hdr.type |= VIRTIO_BLK_T_IN; > - in += num; > - } > } > > - virtblk_add_req(vbr, out, in); > + virtblk_add_req(vbr); > } > > static void virtblk_bio_send_data_work(struct work_struct *work) > -- Asias _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization